Choppin Block back half install help

[FullOutPwr]

So I am installing the Choppin block back half on my 67. I’ve already cut the frame but thankfully left a bunch as the no instructions thing wanted me to be triple sure.

I removed one cab mount and went to check the new Choppin block cab mounts since they center the whole backhalf and new trailing arm crossmember. The new cab mounts have a larger bolt pattern than my stockers. I’m not sure how to line these up, especially as I haven’t seen anyone else on YouTube or google search notching holes just opening them up more for the larger bolts.

Any help? Or did they screw up and send me wrong stuff? The no instructions for this kit make me wish I had thought harder about the brand I went with.